I am an Associate Professor at Texas A&M University, Department of Electrical & Computer Engineering, and a Scientist at Brookhaven National Laboratory, Computational Science Initiative. My research is focused on machine learning and signal processing theories, models, and algorithms for various scientific applications, primarily bioinformatics and computational biology.
In this work, we present a general optimal experimental design (OED) strategy for an uncertain system that is described by coupled ordinary differential equations (ODEs), whose parameters are not completely known. As a vehicle to develop the OED strategy, we focus on non-homogeneous Kuramoto models in this study as the primary example. The proposed OED strategy quantifies the objective uncertainty of the Kuramoto model based on the mean objective cost of uncertainty (MOCU), where the optimal experiment can be identified by predicting the one in a given experimental design space that is expected to maximally reduce the MOCU.
Our study highlights the importance of quantifying the operational impact of the potential experiments in selecting the optimal experiment and it demonstrates that the MOCU-based OED scheme enables us to minimize the objective cost (i.e., cost of robust control in the application considered in this paper) of the uncertain Kuramoto model with the fewest experiments compared to other alternatives.
This work was performed in collaboration with Prof. Youngjoon Hong (Department of Mathematics, Sungkyunkwan University) and Prof. Bongsuk Kwon (Department of Mathematical Sciences, Ulsan National Institute of Science and Technology).
The Brookhaven National Laboratory (BNL), where Dr. Byung-Jun Yoon is working as a Scientist (via joint appointment), has officially joined the ATOM consortium for Accelerating Therapeutics for Opportunities in Medicine (ATOM).
“At Brookhaven, we are excited to apply our team’s work developing and using optimization algorithms directly to ATOM’s diverse computational data-driven modeling efforts,” said Francis J. “Frank” Alexander, deputy director of the Computational Science Initiative. “Often, mathematical models and systems of interest to ATOM cancer therapy problems are uncertain and under-characterized due to their extremely complex nature. At Brookhaven, our artificial intelligence, machine learning and applied mathematics work aims to unravel complexities to design computational and laboratory experiments that achieve discovery goals in the most efficient manner. We believe these efforts will have significant applications in ATOM that can greatly benefit and enhance the program’s impact. We look forward to contributing as part of the collaboration.”
We are happy to announce that our AISTATS 2021 paper entitled “Bayesian Active Learning by Soft Mean Objective Cost of Uncertainty” is now available in the Proceedings of Machine Learning Research, which can be accessed at the following link:
In this paper, we suggest a strictly concave approximation of MOCU – referred to as “Soft MOCU” – that can be used to define an acquisition function for Bayesian active learning with a theoretical convergence guarantee. We show in this study that the Soft MOCU based Bayesian active learning outperforms other existing methods, with the important benefit of theoretical guarantee of convergence to the optimal classifier.
In this paper, we propose an acquisition function for active learning of a Bayesian classifier based on a weighted form of MOCU (mean objective cost of uncertainty). By quantifying the uncertainty that directly affects the classification error, the proposed method avoids the shortcoming of the previous expected Loss Reduction (ELR) methods by avoiding their myopic behavior. Unlike existing ELR methods, which may get stuck before reaching the optimal classifier, the proposed weighted-MOCU based strategy provides the critical advantage that the resulting Bayesian active learning algorithm guarantees convergence to the optimal classifier of the true model. We demonstrate its performance with both synthetic and real-world datasets.
The Applied Mathematics Group of the Computational Science Initiative (CSI) at Brookhaven National Laboratory (BNL) invites exceptional candidates to apply for the Amalie Emmy Noether Fellowship in applied mathematics and scientific computing.
This fellowship offers a unique opportunity to conduct research in a broad set of fields, including reduced order modeling, uncertainty quantification and scalable computational statistics for Bayesian inference, optimization and control for decision making under uncertainty, scientific machine learning, high-dimensional inverse problems, multiscale modeling, integrated computational modeling frameworks, data science for streaming or “in-situ” (within simulation) analytics in high performance computing (HPC), and numerical methods. The methods and fundamental advances made in the course of this research will further the progress of applications of interest to BNL and the Department of Energy (DOE). Examples of such applications might include: data-driven uncertainty quantification and hybrid process-based/data-driven modeling for climate prediction and resilience planning, optimal experimental and simulation design for drug discovery and materials science, and large-scale data processing for particle accelerator experiments. The followship includes access to world-class HPC resources, such as the BNL Institutional Cluster and DOE leadership computing facilities. Access to these platforms will allow computing at scale and will ensure that the successful candidate will have the necessary resources to solve challenging DOE problems of interest.
This program provides full support for a period of two years at CSI. Candidates must have received a doctorate (Ph.D.) in applied mathematics or a related field (e.g., mathematics, physics, engineering, statistics, operations research, or computer science) within the past five years. This fellowship presents a unique chance to conduct interdisciplinary collaborative research in BNL programs with a strongly competitive salary. Recipients will be allowed to select a direct mentor from a list of CSI staff scientists. This mentor will help the recipient define and pursue their own research agenda during their appointment.
We are happy to announce the opportunity to apply for 2021 NSF Math Sciences Graduate Internship (MSGI) to work on the research project entitled: Uncertainty-Aware Data-Driven Models for Optimal Learning and Robust Decision Making Under Uncertainty. (Mentors: Drs. Nathan Urban & Byung-Jun Yoon)
This project aims to develop Scientific ML techniques that enable objective-driven uncertainty quantification (UQ) for data-driven models. We will focus on developing theories and algorithms that can ultimately lead to an automated learning procedure of effective surrogates for complex systems that can be used for making optimal decisions robust to system uncertainties and surrogate approximation errors. These goals will be attained based on a Bayesian ML paradigm, in which we integrate scientific prior knowledge on the system and the available data to obtain a prior directly characterizing the scientific uncertainty in the physical system, quantify the uncertainty relative to the objective, develop optimal operators robust to the uncertainty, and design strategies that can optimally reduce the uncertainty and thereby directly contribute to the attainment of the objective. Potential applications of this methodology will be discussed with the student, but may focus on biological and biomedical discovery science. Detailed information of this project can be found in the project catalog at the following link (search for reference code: BNL-URBAN1): https://orise.orau.gov/nsf-msgi/project-catalog.html
The NSF Mathematical Sciences Graduate Internship (MSGI) program is aimed at students who are interested in understanding the application of advanced mathematical and statistical techniques to “real world” problems, regardless of whether you plan to pursue an academic or nonacademic career. Internship activities will vary based on the assigned research project and hosting facility. As part of your application, you will identify your top 3 research projects from the 2021 NSF MSGI Project Catalog: https://orise.orau.gov/nsf-msgi/project-catalog.html
Drs. Byung-Jun and Xiaoning Qian have jointly launched a new website https://objectiveuq.org, which aims to provide a convenient centralized access point to the latest research findings and developments relevant to objective-based uncertainty quantification (UQ) and optimal experimental design (OED).
This new website will provide a comprehensive list of research papers, software, resources, as well as the latest news and developments relevant to objective UQ. Main topics of interest that will be primarily featured on this new website include:
Mean objective cost of uncertainty (MOCU)
Optimal experimental design (OED)
Robust operator design for operations such as: classification, filtering, compression, control, and clustering
Optimal Bayesian Transfer Learning (OBTL)
Maximal knowledge-driven information priors (MKDIP)
Diverse scientific applications of MOCU and MOCU-based OED
The BioMLSP lab is actively looking for 1~2 MS students and 1~2 PhD students who are strongly motivated to work on emerging research topics that involve machine learning & signal processing with applications in life science and materials science.
Potential applicants should contact Prof. Byung-Jun Yoon via email (bjyoon at ece dot tamu dot edu), which should include: (1) a brief description of the applicant’s general research interests and career goals, (2) CV, (3) undergraduate/graduate transcripts.